This is clear when observing its attachment site on the superior border of the scapula. As the Latin origin word “levator” suggests the main action of this muscle is to elevate the scapula. Another shoulder positioning muscle that can be observed on the posterior portion of the pectoral girdle is levator scapulae. A lot like the trapezius, the rhomboids can also stabilize the scapula on the rib cage.

Both muscles, as evident by their orientation, cause retraction of the scapula, as well as its rotation when lowering the arm from a raised position. The rhomboids are two diamond-shaped muscles that extend from the vertebral column to the medial border of the scapula generally, there appears to be a gap between them but sometimes this is not present and they look like one large muscle. This muscle stabilizes and secures the scapula on the thoracic cage, scapular protraction, and retraction, as well as elevation and depression. This means that the trapezius muscle can be divided into 3 portions, the ascending, transverse, and descending parts, also known as the inferior, middle, and superior parts respectively. This is a large, triangular in shape, and flat muscle its actions can vary based on which region of the muscle is active. Beginning with one of the most dominant muscles in the region, the trapezius. Muscles that position the pectoral girdle are all stated in great detail in the first table below, we will quickly explore some of them, their unique aspects, and their actions. These muscles can be divided up into two groups based on their actions, muscles that position the girdle, more specifically the clavicle and the scapula, and muscles that move the arm. This was an evolutionary trait as a result of the upper limbs no longer needing to be weight bearing limbs now instead of walking using our arms, we became able to hunt, gather and undertake difficult tasks more efficiently with our upper limbs. Despite this being the case the pectoral girdle maintains a large degree of stability mostly due to intricate musculature of the region, all while allowing for some unique movement. As we have mentioned in previous sections, the pectoral girdle or the shoulder girdle sacrifices structural integrity for a greater range of motion.

Coracoid process 3 muscles